IE43950B1 - New 6-amidinopenicillanic acid derivatives - Google Patents

Abstract

1529448 11-Ethoxycarbonyloxy-ethyl 6-(hexahydro-1H-azepin-1-yl-methyleneamino)-penicillanate LEO PHARMACEUTICAL PRODUCTS Ltd AS 8 Oct 1976 [29 Oct 1975] 44676/75 Heading C2C [Also in Division A5] Novel crystalline diastereomeric forms of 11 - ethoxycarbonyloxyethyl - 6 - (hexahydro- 1H - azepin - 1 - yl - methyleneamino) - penicillenate or its hydrochloride are prepared (a) by adding an equivalent of HCl in propanol- 2 to an ethereal solution of mixture of the free base forms, treating the isolated crystals with acetone and recrystallizing them from methanolether to give one diastereomeric hydrochloride, and evaporating the mother liquor and treating the residue with methanol-ether or propanol-2- diisopropyl ether to crystallize the other diastereomeric hydrochloride; or (b) by dissolving the free base in ether, adding cold water, adjusting to pH3À0 with NHCl, freeze-drying the aqueous phase, treating the amorphous mixture with acetone to crystallize one diastereomeric hydrochloride, evaporating the mother liquor, treating the residue with aqueous NaHCO 3 , purifying the liberated base with an ionexchange resin, converting it to the hydrochloride and crystallizing it from ethyl acetate to give the other diastereomeric hydrochloride; or (c) by neutralizing an aqueous solution of the diastereomeric hydrochloride with a base, such as NaHCO 3 to crystallize the diastereomeric base. 11-Ethoxycarbonyloxyethyl 6-(hexahydro-1H- azepin-1-yl-methyleneamino)-penicillinate is prepared as an amorphous mixture of diastereomers by reacting potassium benzylpenicillanate with 1-chloroethylethyl carbonate, treating the resulting 11-ethoxycarbonyloxyethyl benzylpenicillanate with phosphorus pentachloride and quinoline in chloroform, and treating the resulting 11-ethoxycarbonyloxyethyl 6-amino-penicillanate with the dimethyl sulphate complex of N-formyl-hexamethyleneimine.

Description

The present invention relates to the crystalline diastereomeric forms of the compounds of the following formula: and the crystalline hydrochlorides thereof.

Due to the asymmetric carbon atom present in the ester-forming group, as shown in the formula above by an asterisk, the compound of the above formula exists in two different diastereomeric forms, in the following called A and B.

The compounds of the above formula have hitherto been described only as an amorphous product containing a 439 KO - 3 mixture of the diastereomeric forms. This mixture, together with other similar esters of different amidino-penicillanic acids are described in British Patent Specification No. 1,427,139. In that Specification, the preparation of the mixture of the diastereomeric forms has been described and the amorphous mixture is according to Example 1 isolated as a residue. Neither in the specification nor in the Examples has any description of the separation of the mixture into the pure diastereomeric forms been given.

More particularly, the present invention concerns the crystalline form.'' of the free h?ses A ’nd B well as their hydrochlorides, the preparation thereof and pharmaceutical· compositions containing the crystalline compounds A and/or B either in the free form or as their hydrochlorides. The composition may further contain other active and inactive ingredients as mentioned more specifically below.

The mixtures of the diastereomers are known to be valuable antibiotics. They are absorbed well after oral administration and after the absorption the ester-forming group is easily hydrolysed by enzymes present in the organism, giving, rise to the formation of the corresponding free amidinopenioillanic acid, mecillinam, known from Dutch Patent No'. 7016435, corresponding to Patent Specification No. 34620. Mecillinam is a potent antibiotic, especially valuable against gram negative organisms, such as E.coll and Salmonella. Since the stability of compounds of this type is unsatisfactory for pharmaceutical purposes when they are amorphous, whereas in the crystalline state they show a high degree of stability, it is of considerable importance for their practical utilization to obtain them in crystalline state.

According to one embodiment of the method of the present invention the compounds A and B are prepared as their hydrochlorides by adding one equivalent of hydrogen Ξ 0 ο Ο - 4 chloride in propanol-2 to an ethereal solution of the mixture of the free bases. The precipitate which is formed crystallized upon standing. On treatment of the crude crystals with acetone and recrystallization from methanol5 ether or similar solvents the hydrochloride of the pure A form is obtained. When the mother liquor, now enriched in the B form as its hydrochloride, is taken to dryness and the residue is treated with a solvent pair, such as methanol-ether or propanol-2-diisopropyl ether, or combin10 ations thereof, the B form crystallized as its hydrochloride.

In a second embodiment of the method of the present invention, the hydrochlorides of the compounds A and B are prepared by dissolving the free base in ether, there15 after adding cold water and adjusting the pH to 3.0 with N hydrochloric acid. The mixture of the amorphous hydrochlorides is obtained by freeze-drying of the aqueous phase. The crystalline hydrochloride of Compound A is isolated by treatment of the amorphous mixture with acetone.

The mother liquor, now enriched in Compound B, is taken to dryness and treated With aqueous sodium bicarbonate; the liberated base is purified on Sephadex? (registered Trade Mark) and subsequently converted to the hydrochlo- . ride. Treatment of the hydrochloride with cold ethyi ace25 tate gives the crystalline hydrochloride of Compound B.

From the hydrochlorides the free bases A and B can be prepared by neutralizing an aqueous solution of the hydrochloride with a suitable base, such as sodium bicarbonate. Upon standing, the free base of the A and B form, respectively, crystallizes and can be isolated in usual manner.

The preparation of the starting material, i.e, the mixture of the free bases can be performed in known manner by one of the methods described in the above mentioned British Patent Specification No. 1,427,139. The method 3 ίΚ> 0 - 5 used in the present case is described in more detail in the following Examples.

It is also an object of the present invention to provide pharmaceutical compositions adapted for use in the treatment of infectious diseases, and containing as the therapeutically active component the crystalline forms A and/or B or the hydrochlorides thereof mixed with solid or liquid pharmaceutical carriers; auxiliary agents may also be present. Furthermore, the composition can contain other therapeutically active ingredients with a view to combatting bact .vial j·-feet?·' ? .

Pmong such other therapeutically active ingredients mention can particularly be made of the known orally active penicillin and cephalosporin acids as well as their orally active esters.

In the compositions, the proportion of therapeutically active material to carrier substance and auxilliary ayt?nt can vary from 1% to 99% by weight. The compositions can either be worked up to pharmaceutical forms of presentation such as tablets, pills or dragees, or can be presented in medical containers such as capsules, or as far as suspensions are concerned in bottles. The total amount of active ingredients in the composition lies preferably in the range from 10% to 90% by weight of the composition in a form for oral administration. Pharmaceutical organic or inorganic solid or liquid carriers suitable for oral administration can be used to make up the composition. Gelatine, lactose, starch, magnesium stearate, talc, vegetable and animal fats and oils, gum, polyalkylene glycol, or other known carriers for medicaments are all suitable as carriers. Furthermore, the compositions may contain other pharmaceutically active components which can appropriately be administered together with the compounds of the invention in the treatment of infectious diseases, such as other suitable antibacterial agents, 3 9 9 0 - 6 such as sulphonamides and trimethoprim.

Another object of the invention resides in the selection of a dose of the compounds of the invention and a dosage unit which can be administered so that the desired activity is achieved without simultaneous secondary effects.

By the term dosage unit is meant a unitary, i.e. a single, dose capable of being administered to a patient, and which may be readily handled and packed, remaining as a physically stable unit dose, comprising either the active material as such or a mixture of it with a solid pharmaceutical carrier.

In preliminary clinical trials it has been found that the compounds of the invention as the sole active ingredient are conveniently administered in dosage units containing from 0.025 g to 1 g and preferably from 0.05 g to 0.5 g of the substance.

Such dosage units are conveniently administered one to four times a day at appropriate intervals; always however, in accordance with the orders from the medical practitioner and depending upon the condition of the patient. Accordingly, the daily dose will amount to from 0.025 g to 4.0 g of the compounds of the invention as the sole active ingredient and preferably from 0.2 g to 2 g.

Such a daily dose may be administered orally also in the form of an aqueous or oily suspension of the compound of the invention, for which purpose there is appropriately employed a therapeutical composition as described above and containing from 10 mg to 50 mg of such compound per ml of the fluid vehicle.

The present therapeutical composition in dosage unit form may contain, besides a compound of the invention, one of the above mentioned antibiotically active substances, and may result in a synergistic activity.

Suitable penicillins in such a synergistic mixture 3 9 5 0 - 7 can be known, natural, biosynthetic and semi-synthetic penicillins, and in particular penicillins for oral use such as phenoxymethyl-penicillin, ampicillin, amoxycillin and epicillin, and orally active cephalosporins such as cephalexin or cephradin, or easily hydrolyzable esters thereof, such as pivampicillin, bacampicillin and talampicillin.

The synergistic composition can be worked up to any pharmaceutical forms of presentation suoh as tablets, pills, dragees, or suppositories, or the composition can be presented in medic-1 containers such as tspsr.. . tr, as suspensions are concerned, in bottles, tubes, or similar containers.

In such synergistic compositions the compound of the present invention is present in an amount of from 20 to 80% by weight calculated on the basis of the total weight of antibiotically active components, in the form of their free acids, forming the synergistic mixture.

In the treatment of patients suffering from infectious diseases the synergistic compositions are conveniently administered in daily doses from 0.2 g to 4 g, corresponding to the amount of the compound of the invention plus the other antibiotic derivative in question, calculated as free acids, but present as such or as salts or easily hydrolyzable esters thereof.

Appropriately, the daily dose is given in the form of dosage units, e.g, tablets, of which 1-2 tablets are given 2-4 times a day.

Such dosage units can according to the invention contain from 0.1 g to 0.8 g in total of the compound of the invention and the other antibiotic derivative in question, calculated as free acids, but present as such or as salts or easily hydrolyzable esters thereof.

It shall be understood, however that the adequate - 8 doses and frequency of administration may vary, depending upon the condition of the patient and the character of the infection, and shall be determined by the medical practitioner.

Furthermore, according to the invention the dosage unit can appropriately be in the form of tablets, the inner core of which contains one or more of the active components with the necessary pharmaceutical auxiliary agents, whereas the outer core contains the other active component(s) together with adequate auxiliary agents, or such double tablets are provided in which the halves contain their respective component(s) under conditions where no interaction between the components can occur.

The invention will now be illustrated by the follow15 ing, non-limiting Examples.

Example 1 A. 1-Ethoxycarbonyloxyethyl benzylpenicillinate A mixture of potassium benzylpenicillinate (38 g. 0.1 mole), 1-chloroethylethyl-carbonate (20 g. 0.13 mole), sodium bicarbonate (1.5 g), potassium iodide (3 g), water (10 ml) and acetone (250 ml) was refluxed for 16 hours with stirring. The solvent was removed under reduced pressure and the residue was treated with water (150 ml) and ether (250 ml). After washing with water, the organic layer was dried and the solvent was removed in vacuo; light petroleum (300 ml) was added and the mixture was stirred for one hour. The solvent was decanted and the residual oil was dried in vacuo to give 11-ethoxy-carbonyloxyethyl benzylpenicillinate (32 g) as a semicrystalline mass.

B. 1'-ethoxycarbonyloxyethyl 6-aminopenicillanate Phosphorus pentachioride (30.5 g, 0.15 mole) was dissolved in dry chloroform (245 ml) by gentle heating - 9 (40° C). After cooling to 20°C, quinoline (36 g. 0.28 mole) was added under stirring. The mixture was cooled to -15°C, and a solution of 1'-ethoxycarbonyloxyethyl benzyipenicillinate (45 g, 0.1 mole) in dry chloroform (50 ml) was added (10-15 min), maintaining the temperature between -15°C and 12°C. Stirring was continued for 10 min., whereafter ice-cold propanol-1 (87 ml.) was added (20-25 min.) keeping the temperature at -15°C. to -12°C· After stirring for 15 min. at this temperature, icecold 20% sodium chloride solution ¢170 ml.) was added (4 min.), keeping the temperature below -5°C. The organic layer was separated and diluted with ether (500 ml.) and subsequently extracted with 5 portions of ice-cold water (each 100 ml.). The combined aqueous extracts were neutralised at 0°C. with sodium bicarbonate after addition of ether (250 ml.). The organic layer was separated, washed with water, dried and concentrated in vacuo. Light petroleum (250 ml.) was added and the mixture stirred for 30 min. The solvent was decanted and the residue dried in vacuo to give 1 *-ethoxy-carbonyloxyethyl 6-aminopenicillanate (22 g.) as a viscous oil.

The product contained a small amount of quinoline which could be removed by filtration on Sephadex LH 20 using a solvent mixture of chloroform - hexane (65:35).

C. 1'-ethoxycarbonyloxyethyl 6-(hexahydro-lH-azepin-yl)methyleneaminopenicilianate A solution of 1'-ethoxycarbonyloxyethyl 6-aminopenicillanate (3g. 0.1 mole) in ether (330 ml.) was cooled to -25°C, and triethylamine (15.5 ml. O.li mole) added under stirring. Dimethyl sulphate complex of N-formylhexamethyleneimine (28 g. 0.11 mole), dissolved in chloroform (25 ml.), was added (5 min) and the mixture allowed to warm to 0°C., at which temperature the stirring was continued for 1 hour. Water (200 ml.) was added and the - 10 organic layer separated and washed with water, fresh water (400 ml.) was added and the pH adjusted to 3.5 with dilute phosphoric acid at 0°C. The aqueous phase was separated, washed with ether (100 ml.) and neutralised with sodium bicarbonate at 0°C. after addition of ether (200 ml.). The organic phase was separated, washed with water, dried and the solvent removed in vacuo to give a mixture of the two diastereomeric 1'-ethoxycarbonyloxyethyl 6-(hexahydro-1 H-azepin-l-yl)-methyleneaminopenicillanates as a viscous oil (27 g; + 172° (C=l, chci3).

D. The hydrochloride of Compound A was prepared by adding an equivalent of HCl in propanol-2 to an etheral solution of the mixture of the free bases. The precipitate which formed turned partly crystalline upon standing. The crystals were isolated by treatment of the etude hydrochlo-. ride with acetone. Purification was achieved by recrystallization from methanol-ether. The mother liquor, now enriched in Compound B, HCl salt, was taken to dryness and the residue treated with a solvent pair such as methanolether or propanol-2-diisopropyl ether, or combinations thereof, thus inducing the crystallization of Compound B, HCl.

The free bases, Compound A and Compound B, were prepared by neutralising an aqueous solution of the parent hydrochloride with a suitable base such as sodium bicarbonate. Upon standing, the free bases crystallized and could be isolated by filtration. Both compounds exhibited 20 ill-defined melting points with decomposition; values (C=l, CHC13) were + 143 and +198°, respectively. of diastereomers of 1’-ethoxycarbonyloxyethyl-6-(hexahydro-lH-azepin-yl .1 methylene-11- - 12 38 50 Ό β β •ri Ρ β Ο □ Η Η Ej 3 0 ‘j () Example 2 Step D of Example 1 could also be performed in the following lii.iutit'i The mixture of the two diastoromeric 1’-ethoxycarbonyloxyethyl-6- (hexahydro-1 H-azepin-l-yl)-methyleneaminopenicillanates was dissolved in ether, cold water was added and the pH adjusted to 3.0 with N hydrochloric acid. Freeze-drying of the aqueous phase gave the hydro20 chlorides as a colourless amorphous powder (29 g, /o7D + 183° (C=l, H20)).

The amorphous mix cure o*. die ντο diao-.-arenr « - hy'~ rochlorides was dissolved in cold acetone (100 ml.) and crystallization was induced by scratching. After stirring for two hours at 0°C. the crystals were filtered off (10 g.) and reerystallized from methanol-ether to yield the pure hydrochloride of Compound A as colourless crystals, mp 166°C. (dec.), /ct/^0+ 168o (c=1/ , The acetone filtrate was rapidly taken to dryness in vacuo. The residue was dissolved in cold water and neutralized with (solid) sodium bicarbonate. The liberated base was extracted with ether and purified by filtration on Sephadex LH 20 (solvent: ohloroform-hexane (65:35)). After evaporation of the solvent, the residual base was converted into its hydrochloride as described above (12 g).

This hydrochloride, now enriched in Compound B, was dissolved in ethyl acetate and crystallization and purification were performed as described above to give the pure hydrochloride of Compound B, mp 164°C. (dec.) /07^° + 195° (¢=1, H20).

EXAMPLE 3 Preparation of tablets containing 11-ethoxycarbonyloxyethyl-6-/7hexahydro-lH-azepin-l-yl)-methyleneaminq7u ·> G 0 - 14 penicillanate hydrochloride, A-form.

Ingredients: 1’-Ethoxycarbonyloxyethyl 6-/lhexahydro-lHazepin-l^ylj-methyleneamingy-penicillanate 5 hydrochloride, A-form, m.p.: 16O°C(dec) /ά/§° +213° (c 1; CHC13) 350g. Polyvinylpyrrolidone log. Corn starch 40g. Magnesium stearate 4g.

The 11-ethoxycarbonyloxyethyl ester is screened through a sieve with 1.0 mm mesh openings. The powder is then wetted with a solution of polyvinylpyrrolidone in 150 ml of a solvent composed of 1 part of ethanol (96%) and 19 parts acetone. The moist mass is passed through a sieve with 1.0 mm mesh openings and then dried at 30°C, on trays or other convenient drying equipment, for instance a fluidized bed dry cupboard.

When the solvent has evaporated, the granules are sifted through a sieve with 0.7 mm mesh openings, and are finally mixed with the corn starch and magnesium stearate.

The granule is compressed into tablets of 0.40 g. weight using punches and dies of 12 mm. diameter to yield 1000 tablets each containing 0.35 g. of the 1'-ethoxycarbonyloxyethyl 6-/(hexahydro-lH-azep:Ln-l-yl) -methylene25 amino7-penicillanate hydrochloride, A-form.

Example 4 Capsules, each containing 0.150 g of 1'-ethoxycarbonyloxyethyl 6-Z|hexahydro-lH-azepin-l-yl)-methyleneaminq7“penicillanate hydrochloride, A-form and 0.175 g. of 1'-ethoxycarbonyloxyethyl a-aminobenzylpenicillanate hydrochloride are prepared according to the following procedure: Ingredients: 1'-ethoxycarbonyloxyethyl 6-/(hexahydro-1Hazepin-l-yl)-methyleneaminq7-penicillanate hydrochloride A-form 11ethoxycarbonyloxyethyl a-aminobenzylpenicillanate hydrochloride Polyvinyl pyrrolidone 150 g 175 g g.

Magnesium stearate g. 1'-ethoxycarbonyloxymethyl 6/(hexahydro-lH-azepin1 - yl) -methylent·.ut:'πο/’ penicil.lunato k_ Irocklcridc d 1·ethoxyoarbonyloxyethyl a-aminobenzylpenicillanate hydrochloride are mixed and passed through a 20 US Standard mesh sieve. After having been mixed again, the resulting powder is moistened with a solution of polyvinyl pyrrolidone in isopropanol (150 ml.). The moistened mixture is granulated by passing it through a 20 US Standard mesh sieve and is afterwards dried at 30°C. For the drying operation, a conventional drying oven with trays, or other suitable drying apparatus, for instance functioning according to the fluidized bed principle may be applied.

After drying, the granulate is passed through a 25 US Standard mesh sieve and is finally mixed with the magnesium stearate.

Hard gelatine capsules No. 0 are fitted with the finished granulate, each capsule containing 0.349 g. granulate, the above ingredients thereby corresponding to 1000 capsules.

Example 5 For oral suspension the following formulation was prepared. 3 9 Β Ο - 16 11-ethoxycarbonyloxyethyl 6-hexahydro-lHazepin-1-(yl)-methylenearaino-penicillanate mixture of crystalline A form and crystalline B form (1:1) 8 g.

Sodium benzoate ,0.5.g Sodium chloride 1 Flavouring agents 5,g.

Aerosil (registered Trade Mark) 0.3 g Alkali metal salts of polysaccharide 10 sulphates 2.0 g Sucrose ad 100 g.

Claims (12)

1. CLAIMS: 1. The crystalline diastereomeric form A of the hydrochloride of the compound of the following Formula I 5 CII 3 charterized in having a melting point of 166°C. (dec), an y2O of +168° (C=l, HjO), and an NMR-spectrum as shown in Table I herein.

2. The crystalline diasteromeric form B of the hyd10 rochloride of the compound of the formula I of claim 1, characterized in having a melting point of 164°C. (dec.), an of +195° (C=l, H 2 0) and an NMR-spectrum as shown in Table I herein.

3. The crystalline diastereomeric form A of the com15 pound of formula I of claim 1, characterized in having an /q7p° of +143° (C—1, CHClg) and an NMR-spectrum as shown in Table I herein.

4. The crystalline diastereomeric form B of the compound of formula I of claim 1, characterized in having an 20 /Vd° of +19θ° (C=l, CHC1 3 ) and an NMR-spectrum as shown in Table I herein. X 433 50 - 18

5. A crystalline diasteromeric compound of the formula given in Claim 1 or the hydrochloride thereof, substantially as hereinbefore described in Example 1 or 2 of the foregoing Examples.

6. A pharmaceutical composition comprising as the therapeutically active component a crystalline diasteromeric compound as claimed in any one of Claims 1 to 5 or a mixture thereof, together with a solid or liquid pharmaceutical carrier.

7. A composition as claimed in Claim 6, wherein the proportion of therpeutlcally active component to carrier is from 1% to 99% by weight.

8. A composition as claimed in Claim 6 or 7, wherein the composition is presented in a form for oral administration and comprises from 10% to 90% by weight of therapeutically active component.

9. A composition as claimed in any one of Claims 6 to 8, wherein the therapeutically active component comprises one or more Other antibiotics.

10. A composition as claimed in any one of Claims 6 to 8, wherein the composition is in the form of a dosage unit containing from 0.025 g. to 1 g. of said crystalline diastereomeric compound(s).

11. A composition as claimed in any one of Claims 6 to 8, wherein the composition is in the form of a dosage unit·containing from 0.05 g. to 0.5 g. of said crystalline diastereomeric compound(s).

12. A composition as claimed in any one of Claims 6 to 9, wherein the composition is in the form of an aqueous or oily suspension containing from 10 mg. to 50 mg. per ml. of said crystalline diasteromeric compound(s). - 19 1J. A pharmaceutical composition aubutantiaily aa hereinbefore described in any one of Examples 3 to 5 of the foregoing Examples.